The invention relates to a medium or high voltage electrical circuit breaker having per pole a support for two vacuum cartridges each of which contains a pair of separable contacts. The pairs of separable contacts are electrically connected to each other in series by an electrical connection to increase the voltage withstand of the pole and, each pair comprising a movable contact which is connected by a mechanical connection to open and close the two pairs of contacts simultaneously.
A state-of-the-art circuit breaker of the kind mentioned, comprises two vacuum cartridges, arranged one above the other, inside an elongated support, borne by an insulating console secured to a frame. It is known that the dielectric withstand of vacuum cartridges is limited and that it is extremely difficult to exceed surge voltages of 100 to 250 KV. By connecting two or more cartridges in series, it is possible to increase this dielectric withstand notably and to achieve medium or high voltage circuit breakers. The above-mentioned state-of-the-art circuit breaker is very voluminous and cumbersome, and requires a large operating energy, practically twice that of a single cartridge. Incorporating such a circuit breaker in a cubicle gives rise to serious problems to which should be added the risks of overheating which are also doubled.
The object of the present invention is to achieve an electrical vacuum cartridge circuit breaker having a notably increased dielectric withstand.